116 PROOFS OF LONG LAPSE OF TIME. 
sometimes losing whole families, which are re- 
placed by new ones, have pervaded the entire 
range of fossiliferous formations. 
The most prolific source of organic remains 
has been the accumulation of the shelly coverings 
of animals which occupied the bottom of the sea 
during a long series of consecutive generations. 
A large proportion of the entire substance of 
many strata is composed of myriads of these 
shells reduced to a comminuted state by the 
long continued movements of water. In other 
strata, the presence of countless multitudes of 
unbroken corallines, and of fragile shells, having 
their most delicate spines, still attached and un- 
disturbed, shows that the animals which formed 
them, lived and died upon or near the spot 
where these remains are found. 
Strata thus loaded with the exuviae of innu- 
merable generations of organic beings, afford 
strong proof of the lapse of long periods of time, 
wherein the animals from which they have been 
derived lived and multiplied and died, at the 
bottom of seas which once occupied the site of 
our present continents and islands. Repeated 
changes in species, both of animals and vege- 
tables, in succeeding members of different form- 
ations, give further evidence, not only of the 
lapse of time, but also of important changes in 
the physical condition and climate of the ancient 
earth. 
Besides these more obvious remains of Tes- 
